(1) Field of the Invention
The present invention relates to a winged vehicle which is mounted on T-shaped rails by means of a T-shaped slot in the vehicle. In particular the present invention relates to a winged vehicle which uses magnetic attraction means between the rail and vehicle to levitate the vehicle as the wings provide lift.
(2) Prior Art
Magnetically levitated Maglev trains, propelled by linear induction motors, have been under development for many years. Hermann Kemper, a German, first developed the concept in 1935. However, his development went without notice until 1960, when two companies, Kraus-Maffei and Messerschmitt-Bolkow-Blohm, began development work with financial aid from the German government. Currently, there are basically two kinds of magnetic levitation, using either (1) repulsive force between vehicle-borne superconducting magnets and induced currents in guideway conductors, or (2) attractive force between iron-core electromagnets on the vehicle and ferromagnetic rails. The first type is referred to as electrodynamic suspension (EDS), and the second type is called electromagnetic suspension (EMS). Their characteristics are given in Table 1.
TABLE 1 ______________________________________ Characteristics of Maglev Systems EDS(repulsion mode) DMS(attraction mode ______________________________________ Magnets superconducting Iron-core electro- coils magnets Guideway Aluminum strips or Laminated or solid components multiple-turn ferromagnetic coils strips Liftoff speed 40 to 80 km/h Magnetically sus- pended at all speeds Guideway 100 to 150 mm 10 to 15 mm clearance Stability Dynamically stable: Inherently unstable: no feedback con- feedback control trol necessary; necessary to damping required maintain dynamic for good ride stability quality Compatible Air-core linear- Iron-core linear propulsion synchronous motor synchronous motor systems or linear induction motor ______________________________________
Maglev trains are in commercial service, one connecting the Birmingham, England airport with a rail terminal in the National Exhibition Centre, and the other is the German transrapid (TR) 06 vehicle.
All attractive systems need a variable-voltage, variable-frequency inverter to supply the power. On a large vehicle, this is a heavy piece of equipment. The situation may be alleviated somewhat by putting the excitation on the guideway. The inverter then becomes ground equipment instead of vehicle equipment and the weight and cost of the vehicle goes down. Had the powered magnets been aboard, the whole train would be full of inverters, since the kVA (kilo-volts times amperes) required at high speeds is very great. By having the power on the wayside, the vehicles are a lot lighter and cheaper, but guideway costs are higher.
Repulsive levitation also has its drawbacks, although the system gets better as it gets bigger. Repulsive levitation requires wheels or another means of suspension for slow-speed running. This is because the current strength and repulsion field induced in the coils or continuous metal plates provide lift only when magnets reach 20 mph. Superconducting magnetic fields will penetrate an aluminum sheet until at about 20 mph the eddy-current magnetic field repels it. Another problem is the magnetic drag inherent in repulsive levitation. As the vehicle begins to pick up speed, magnetic drag climbs steadily, although at about 20 mph it begins to fall off.
As for maglev propulsion, Siemens' initial design of a repulsive-levitation vehicle calls for a double-sided linear induction motor (LIMK) in the vehicle straddling a continuous vertical reaction rail along the guideway. The on-board sandwich-type primary windings correspond to the fixed armature surrounding the spinning rotor in an ordinary motor. The magnetic field of the LIMK windings induces currents and opposing fields in the fixed reaction rail (secondary), which corresponds to a rotor. The interaction of opposing fields spins the rotor in an ordinary motor, but thrusts the LIMK primary and attached maglev vehicle linearly along the reaction rail. Such on-board LIMK primaries requires enormous electrical input through flexible collection arms that make contact with power rails paralleling the guideway. Thus, the major obstacle, is the shortage of electrical energy. A major breakthrough in electrical generation (like fusion power) must happen first, before high-speed maglevs become practical.